Electric transformer



(No Model.) 3 sheets-sheen 2 v J. J. WOOD.

ELBGTRIG TRANSPORMER. No. 511,574. Patented Deo. 26, 1893.

FIG'. 4.

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` INVENTOR: WITNESSES: gn/n W QW By /zfs fzomeys, 1f. KQPMM` sssssssssssss s.

(No Model.) 3 sheets-sheet 3, J. J. Woon. ELECTRIC TRANSFORMBR.

No. 511,574. Patented Deo. 26, 1189s.

l, INVENTOR: WITNESSES.

THE NATIONAL Lx-mcamrums cownnv.

UNITED STATES PATENT OFFICE.

JAMES J. VOOD, OF FORT VAYNE, INDIANA.

ELECTRIC TRANSFORM ER.

SPECIFICATION forming part of Letters Patent No. 511,574, dated December 26, 1893.

Serial No. 474.761. (No model)y To @ZZ whom it may concern.'

Be it known that L JAMES J. VOOD, a citizen of the United States, residing at Fort -Wayne, in the county of Allen and State of Indiana, have in vented certain new and useful Improvements in Electric Transformers, of which the following is a specification.

This invention relates to the construction of transformers or converters, called closed magnet-circuit transformers, for use with alternating currents, to transform a current of high electro-motive force on a main or line circuit, into one of lower electro-motive force but greater volume on a secondary or local circuit. Such transformers are commonly constructed with the primary and secondary coils wound together in any suitable arrangement, and with a laminated iron envelope entering between and surrounding the coils or the greater portion thereof, transformers as thus constructed being known as iron-clad transformers. In the construction of such transformers the coils are usually irst wound and the laminated iron envelope is afterward applied. ln some constructions each layer or lamina of the envelope is made of a single sheet iron punching, which in order to enable it to be applied to the coil is slitted` across or cut open on one side so that its legs may be bent or sprung apart to pass them around the coil, alternate laminoe being applied from opposite sides so as to break joints; this construction is objectionable because of the difticulty of thus applying the laminae to the coil, which makes the building up of the laminated envelope unduly expensive. According to other constructions the laminated envelope is made in two or more sections, each of which is built up of sheets or punchings before being applied to the coil, and the seetions being applied from opposite sides so as to fit together with abutting joints. Constructions of this character are objectionable by reason of the interruption to the magnetic circuit caused bythe complete break in the metallic connection at the abutting joints, whereby the magnetic resistance is increased and the eiiiciency of the transformer is reduced.

My invention aims to provide an improved construction of the iron envelope which shall combine the lowest magnetic resistance with the least expense in assembling the parts of the transformer.

To this end my invention provides an improved subdivision of the respective lamina of the envelope of an iron-clad transformer in the manner hereinafter fully described.

Figure 1 of the accompanying drawings is a sectional elevation of a transformer of the character to which my inven tion is applicable, the iron envelope being partly in section in the plane of the line l-l in Fig. 2. Fig. 2 is a transverse section thereof in the plane of the line 2 2 in Fig. l. Fig.8 is a plan of the two pu nchings constituting one lamina of the iron envelope. Figs. et to S inclusive are similar views to Fig. 3, showing mcditied shapes of punchings forming the laminze.

In Figs. l and 2, let A designate the Wire coils, andB the magnetic envelope. The coils consist of a primary coil p and a secondary coil s, as shown in section in Fig. 2, separated and inclosed by insulating layers a according to any suitable construction, and the primary aud secondary being arranged together in any manner known in the art, either in the manner shown in Fig. 2, or by winding the primary inside the secondary, or by winding them alongside of each other, or in alternate layers, or in any other way desired, the winding of the coils being immaterial to myinvention. l have shown the rounded ends of the coils beyond the magnetic envelope as being supported on grooved blocks b b as usual.

The magnetic envelope B is built up of any suitable number of superposed layers or laminze of sheet iron, of any suitable or usual thickness or quality. Each layer or laminze consists of two punchings, shown separately in Fig. 3, and lettered O O. The two punchings O are applied on opposite sides of the coils A, and their meeting edges abut in planes between the opposite side planes of the coils. Each punching consists of an outer band d d extending from end to end, and of limbs c f and g projecting from it in the manner shown in the preferred construction in Fig. 3. Preferably the two pun chings are exactly alike, one of them being reversed relatively tothe other, and the conformation of the ends of their limbs being such that when thus reversed they will lit together with a close joint7 as shown in Fig. 2. The limbs e g together constitute the portion of the envelope surrounding th'eouter side of the coil, while the limbs ff together constitute the core or middle portion of the envelope which lies within the coils. The limbs e f g of each punching are of unequal length on opposite sides ot'7 the axial plane of the coils (this plane being denoted by the line xx in Fig. 2), so that by reversing the alternate or successive pairs of punchings, the limbs are overlapped so as to break joints, in the manner shown by a comparison'of the full and dotted lines in Fig-2.

In order that the limbs may be 'of' unequal length on opposite sides of the axial plaue'of the coils, the middle limb f is made of a greater length on one side of its middle than on the other side thereof, so that when two pairs of punchings or laminae are reversed and superposed, the elongated portions f of their middle limbs overlap 'each' other, 4as shown in` Fig.' 2. The middle 1 limbsy f are preferably kmade in a reverse curve, as shown in'Figs: 2 and 3,in order to avoid anyangles,

and to bring the superposed joints where they cross eachother nearly into line with the "magneticliues of force. Y, y

The form ofY punching shown in Fig. -3 is preferable, as it aifords a considerable economyofmetal, avoiding undue waste in the process ofL pu-nching from a plate or strip, and because it secures the maximum'overlap of the middle limbs of the laminze, as Well as avoiding'any ycontinuity ofV the superposed joints where they-cross.l Other forms'y are shownl in Figs: 4, 5 andti, which 'are' nearly as effective.v InF-ig. 4 the limbse and g arev the-same, butthe limb fis different in that instead ofits meeting edge being formed with shown-,iso thatthe longer portion f thereof is rectangular. In Fig. 5 theouter limbs'e g arethe same, but the middle limb j' is cut diagonally, asclearly shown. Inl Fig. n6 ally three limbs e f g are cut diagonally on the same line, a construction which is less desirable lthan the preceding, because' it `greatly reduces lthe amount of overlap of the oppositeside portions of the middle limb f, as is apparent. v

Fig. 7 shows afurther modification in which theshort end limbs g are entirely suppressed, their place being taken by a corresponding elongation letteredf e of the' lon-g end limbs e. mig-hebbe44 of the form shown in either of the four preceding figures'. l As here shown this middle limb'is most nearly like that shown in Fig. 4, differingtherefrom only in that the corners or anglesare rounded.

The shapeofl punching shown in Fig. 7 is somewhat less desirable than the preceding, because the end joints 'y y cannot be forced into close contact by pressure applied flatwise at'thewopposite sides of the coil and in line with theaxial plane thereof, but require a diagonal pressure between its corners.

a reverse curve it is formed angularly as With this modiication'the middle limb f' punchings are properly-arran'ged',f and has In assembling either shapes of punchings shown in Figs. 3 to 7, in all of which each lamina is madeup of two like punchings relatively reversed so as to fit to each other, it is only necessary for the operative to bring the two punchings together from opposite sides of the coil until theyfcome in contact edge to edge and complete one layer or lamina, and then for the next lamina to bring together twopunchin'gs' relatively reversed so as to break joints, as shown by a comparison of the full and dottedlines indicating the abutting jointsin the yseveral figures, and to repeat this 'operation ofv'alternating or reversing every successive layer until the magnetic envelope is built upto the-desired height.

lVhile it is preferable to reverse everyfalternate layerin order to mostfcofmpletelyl break' j joints, yetit will answer if two, three or more of the laminae are superposed with their joints in coincidence, andthenthelnext two,tl1ree or more laminre are superp'ose'd'with their joints -in coincidence withfeach 'other but `reversed "so as to break' joints with the .first "se ries of lam-inse; and soon. Tliis,'how'ever, is not recommended, but is mentioned Al'only to call attention to a possible 'and immaterial variation in arrangement;

Fi'gfS sho-ws .an additional' modification wherein each lam-ina is lmade of two unlike punchingsfletteredC2 C3, applied atopposit'e sides of the coils'andhaviiig limbs'v of unvequa-l length as comparedwith one another,

the three limbs of'Y each punching;-however, being oflike length; As'shown, the'pu-nclring Czhas three limbswhich projectbeyond Y themiddle of the'coils for aicert'ain suitable ldistance, while' the `punching C3' hasthr'ee limbswhich project to an equal'distanceles'sl than the middle ofthe icoils-,sothatby bring-n ingV together these two punchingsf 'edgef'to edge, and then superposing-upon* themalf-j vother pair of like punchingsirelati'vely: vre'- versed, as shown in'dottedllines;th'e'respectivey joints 'are broken' "or" alternated." This construction is less' desirable thani those previously described, beca'usefof' the requirement 'oftwo different punchings; it 'beingpracti#k 'cally-of greatadvantage'to havebu't one kind of punchings for eachlsiz'e oft'ransforiner en# velope, thus necessitating only -oneset of dies" for forming the punchingsan'denabling""thex envelope to beassemlble'd more rapidly `be-VA causethe workman has merelyto kvsee that the' not to ings# I claimas my invention-'the followingde# fined novel features, substantiallyasherein# before specified,I n'arnelyz' nated iron envelope havinggits laminee-'made each of two sh'eetiron"punchingsctting to4 gether from opposite sidesof' vthe fcoils," and each having a` middle limb entering within the coils and the two'p'unchings h'avingtheir relatively abutting limbs of unequal length IOC IIO

at the points where they abut, so as to meet each other out of coincidence with the middle of the coils, and with successive laminze reversed so that by the unequal length of their limbs they shall break joints.

2. An iron-clad transformer, the laminated envelope of which is built up of laminze made each of two sheet-iron punchings fitting together from opposite sides of the coils, each punching having a middle limb entering within the coils, their middle limbs being of unequal lengt-h on opposite sides of the axial plane of the coils, and with sueeessivelamine reversed to break joints.

3. In an iron-clad transformer, the laminated iron envelope built up of like sheet iron punehings fitting together from opposite sides of the coils, said punehings having each a middle limb entering within the coils and JAMES J. WOOD.

Vitnesses:

OeTAvIA STEWART, H. J. MILLS. 

